Apparatus for the production of bound bodies of bulking clay

ABSTRACT

An apparatus for the production of ceramically bound bodies of bulking clay which comprises a housing defining a passage-through chamber, adapted to blow alternately highly heated gas in opposite directions through a heap of debris of a granulate capable of swelling in a form box received in the chamber up to swelling and ceramic binding of the surfaces of the granulate. A gas feeding device and a heat storage are provided. The passagethrough chamber includes the heat storage in the direction of the flow of the gas driven alternately back and forth on both sides of the form box. A burner feeding device for a gaseous mixture is arranged which operates controlled and regulated. Chamber sections are disposed between the heating storage and the form box. The chamber sections constitute burner chambers, and a flue gas branch is disposed within the range of the gas feeding device.

United States Patent [1 1 [1111 3,740,182 Wiinning [4 11 June 19, 1973 APPARATUS FOR THE PRODUCTION OF Foreign Application Priority Data Nov. 30, 1970 Germany P 20 58 789.7

U.S. Cl 425/446, 425/383, 425/387 Int. Cl. B29c 1/00, B29f 5/00 Field of Search 425/109, 384, 470,

References Cited UNITED STATES PATENTS 8/1939 Flotron 425/445 X 11/1964 Harrison 425/445 X 6/1966 Butow et al 425/446 X Primary ExaminerRobert L. Spicer, Jr. Attorney-Ernest G. Montague [57] ABSTRACT An apparatus for the production of ceramically bound bodies of bulking clay which comprises a housing defining a passage-through chamber, adapted to'blow alternately highly heated gas in opposite directions through a heap of debris of a granulate capable of swelling in a form box received in the chamber up to swelling and ceramic binding of the surfaces of the granulate. A gas feeding device and a heat storage are provided. The passage-through chamber includes the heat storage in the direction of the flow of the gas driven alternately back and forth on both sides of the form box. A burner feeding device for a gaseous mixture is arranged which operates controlled and regulated. Chamber sections are disposed between the heating storage and the form 8 Claims, 4 Drawing Figures Patented June 19, 1913 3,740,182

4 Sheets$heet J.

Patented June 19, 1973 1 3,740,182

4 Sheets-Sheet 3 Patented June 19, 1973 0.182

4 Sheets-Sheet 5 HT dam t 6L Patented Jun 19, 1973 3,740,182

4 Sheets-Sheet APPARATUS FOR THE PRODUCTION OF BOUND BODIES OF BULKING CLAY The present invention relates to an apparatus for the production of ceramically bound bodies of bulking clay with a passage, in which a heap of debris of granulate capable of swelling is blown through in a form chest up to swelling and ceramic binding of the granulate surfaces alternately in opposite directions with highly heated gas.

Such device has been proposed already, in order to heat granulates, from which ceramically bound bodies are to be produced from bulking clay, by a gaseous operating medium up to the temperatures, at which the swelling and ceramic binding occurs. It is of essence, that at least in the critical range of the swelling temperatures and of the melting of the granulate surfaces capable of ceramically binding great quantities of heat can be released within a short time by the gaseous heat carrier to the granulate capable of swelling. By the setting-in of the swelling process, the gap spaces between the granulates in the formed heap of debris start to clog up, so that a further heating by means of passing through gas is no more possible. During the feeding of the gaseous working medium through the heap of debris of granulate, in addition also the chemical charac' ter of the gas must be controlled in predetermined manner, because namely the temperature ranges, in

which the swelling sets in, and in which the surfaces of.

the granulates melt, can be displaced, depending upon the fact, whether the gaseous heat carrier has chemically oxidizing or reducing character. In addition to an exact temperature, pressureand speed-control of the gaseous working medium thus also a non-objectionable influence of the chemical character must be possible. The swelling range and the temperature range, in which clays or other corresponding working material become capable of ceramically binding, is in clays mostly in question or other materials capable of swelling are above 1000C, so that the gaseous working medium must have temperatures, which are in the range, in which normal steels start to soften. In the proposed device the gas is heated to the required temperature and blown off after the passing through of the heap of debris, so that a relatively great energy expenditure is required.

It is one object ofthe present invention to provide an apparatus of the type stated above, and that it is capa ble of performing, with a simple, robust and reliable structure, the heating of the granulate with a high thermic efficiency and with exact control of the characteristics of the gaseous working medium, which characteristics are essential and influencing the production process.

it is another object of the present invention, to provide an apparatus of this type stated above, wherein the passing through chamber in the path of the stream of the gases alternately reciprocating has on both sides of the form box a heating storage each, whereby the chamber sections disposed between these heat storages and the form box are formed as burner chambers by connection with a controlled and regulated working burner-feeding device for a gaseous mixture and that within the range of the gas feeding device a fuel-gas connection branch is provided.

In accordance with the present invention the gas is driven in a relatively cool state from the gas feeding device at first through a heat storage, then through the burner chamber and thereafter through the heap of debris capable of swelling and disposed in the form box. The heating of the gas to the required working temperature takes place in the heating storage. When the gas has cooled off after passing the heap of debris in the form box and emerges from the heap of debris, it enters a second burning chamber and is again heated up here by feeding a controlled and regulated burnable gaseous mixture to a predetermined temperature corresponding with the prevailing working conditions and driven through the heating storage following in the direction of the stream. In this storage the gas releases an essential part of its heat and emerges in a comparatively cool state from the heating storage. Upon a change of direction of the gas movement, cool gas is fed into'the freshly heated heating storage and after passing the burner chamber through the form box with the granw late capable of swelling and disposed therein. In the burning chamber following in the direction of the stream takes place again the heating of the chamber, in order to heat the following heating storage in the direction of the stream and cooled by the previous stream process. Several working plays of this type follow within short time intervals. Though preferably a heating takes place in the burning chamber, which is arranged in the direction of the stream on the exit side of the form box, a burnable mixture can be fed also, in case the working conditions require it, into the burner chamber, which is disposed on the entrance side of the form box.

In accordance with the present invention, an essentially constant closed gas volume is moved back and forth in a pendulum manner alternately in opposite directions through the passage through chamber. The flue gas branch within the range of the gas feeding device serves merely the purpose, to feed off the over flow gas quantities, which result such, that the gaseous mixture is fed into the burner chambers. An essential advantage of the present apparatus resides in the fact, that the gas feeding device moves relatively cool gas. Accordingly, the gas feeding devices as well as the stream-, conductivity and guiding-elements can be produced of normal working material. Also concerning the efficiency essential advantages in the apparatus designed in accordance with the present invention, since it is possible very simply, to provide, that the gas temperature in the working burner chamber and the exit temperature of the gas after passing the heating storage in exit direction from the passage through chamber are at a ratio of about 3:1 relative to each other. In a rough generalization this means that upon neglect of pressure variations, that a corresponding volume variation of the gas takes place, so that the gas feeding device has to provide merely a very low feeding volume, in order to be able to drive the required large gas volume through the heap debris in the form box. Since the heap of debris in the form box in comparison with the burner chambers on both sides and the heat storages connected herewith has an only narrow-or small passage cross-section, high gas stream speeds result in the heap of debris, without necessity that high stream speeds must be produced outside of the heap of debris.

The apparatus designed in accordance with the present invention operates with a high thermic efficiency, since the heating storages disposed on both sides of the heap of debris to be passed prevent that large heat quantities can be lost. Instead a certain quantity of heat moves in pendulum fashion with the gas stream between the two heat storages back and forth. Thereby continuously heat is released to the heap of debris from the granulate capable of swelling, however by controlled mixture feeding in the burning chamber is fed thereto again. Due to the fact that the superfluous gas quantity to be fed off for maintaining constant the working gas volume, which superfluous gas quantity is produced in the burner chambers by the heating process is fed off within the range of the gas feeding device only in the cooled state within the range of the gas feeding device, an essential part of the heat of these flue gases are retained.

Since in the apparatus designed in accordance with the present invention, an essentially constant gas volume is enclosed as a working medium, it is very easy, to control the chemical character of this closed gas volume in the burner chamber depending upon the requirements, by feeding in, if necessary, a mixture with oxygenor burning material-surplus, in order to create an oxidizing or reducing character of the gas. It can be an advantage thereby,.to feed a mixture to the burner chamber disposed at the entrance side of the form box, in order to render effective the produced gas character directly on the granulate in the heap of debris.

In addition to the above stated, stream-technical, thermic and control-technical advantages the apparatus designed in accordance with-the present invention is also characterized by the fact, that no movable elements, control devices or the like have to be exposed to the highly heated gas being at working temperature. Since also the gas feeding device has to move only cool gas, the apparatus can be formed robust and reliable in spite of the use of simple and price-favorable working material.

It has been mentioned already, that for the required gas passage through the heap of debris in the form box, only a comparatively small gas volume has to be moved from the gas feeding device. In an advantageous further development of the present invention, thus the gas feeding device is equipped with a controllingly driven double piston, which moves back and forth the substantially closed gas volume between its both pistons through the form box, the burning chamber and the heat storage.

The double piston can thereby be disposed in a conduit, which follows on the down-stream side the heating storage. Alternately, the gas feeding device can also consist of two mechanically separated, yet drivingly connected individual pistons, each of which is disposed in the down-stream sided stream path behind each heat storage in the passing-through chamber itself.

While by use of the mentioned pistons as gas feeding device the constant gas volume can be kept relatively small, and a very fast direction change of the gas stream can be produced, it is advisable to form the gas feeding device as a direction-reversible blower and to dispose the same in a conduit, which connects the downstream sides of the heat storages, if a larger gas volume is required or advantageous and if the heap of debris in the form box is to be passed by the gas for a longer time period in one direction. The capacities of the heat storages have to be considered thereby, since when the latter have released their heat in one working play, it is suitable, to reverse the direction of the gas stream, in

order to perform again the heating of the heating storage.

The thermic efficiency of the apparatus designed in accordance with the present invention, can still further be improved, when the gases of the heat storages emerge from the passage-through chamber are fed still through a gas cooler. Such gas cooler can remove further energy from the gas, which can be applied usefully for many purposes. With such gas cooler an additional volume reduction takes place. The gas quantity released at the flue gas branch is thereby smaller and the heat quantity removed by this gas quantity is likewise essentially reduced.

An increase of the energy exploitation permit further formations of the apparatus, in which an air conduit branches off from the burner feeding device and is connected with the suction side of the blower or with the pressure chambers disposed directly in front of the pistons for the gas feed. By means of these conduits the combustion air required for the mixture formation is selectively supplied as a part thereof or also exclusively into the gas feed back and forth. In devices with pistons the supply of the air takes place always in the chamber, in which the piston produces pressure.

By this air feed, a relatively strong dilution of the oxygen on the upstream side of the chamber is achieved, and the percentual share of the oxygen of the total volume of the gas is relatively small. The combustion of the mixture created in the burner chamber takes place with this air feed thus not spontaneously, rather retarded. To the full extent the combustion takes place only in the form box under catalytic influence of the granulate. This process leads to the very appreciable advantage, that the combustion heat is created directly at the place, where the requirement for heating the granulate exists. The heating can thus take place at least at a certain percentage thereof without heat transportation by the gaseous working medium. By this arrangement, for this heat proportion produced and consumed directly in the form box, also all losses unavoidably connected with a heat transportation are removed.

With these and other objects in view, which will become apparent in the following detailed description, the present invention, which is shown by example only, will be clearly understood in connection with the accompanying drawings, in which:

FIG. 1 is a longitudinal section of a first embodiment of the apparatus designed in accordance with the present invention;

FIG. 2 is a view of a second embodiment of the apparatus, shown partly in elevation and partly in section;

FIG. 3 is an elevation of a third embodiment of the apparatus, shown partly in section; and

FIG. 4 is a fragmentary section of a fourth embodiment of the apparatus.

Referring now to the drawings, the apparatus, designed in accordance with the present invention, serves the production of ceramically bound bodies of bulking clay. The apparatus comprises a body 1 which defines a passage-through chamber 2, in which granulate3 capable of swelling, of which the ceramically bound bodies of bulking clay are to be produced, are received in form of a heap of debris in a form box 4. The form box 4 is suitably rollable in and out by means of appropriate devices from the passage-through chamber 2.

The granulate 3 is heating in the form box 4 in the passage-through chamber 2 by passing through highly heated gas, until the swelling process sets in, and the surfaces of the granulate become capable of ceramically binding. In order to permit, that the heap debris of the granulate 3 in the form box 4 can be passed by the gas, the form box 4 must have a permeable sievelike bottom 5, and if a cover is used, also a gaspermeable cover.

The passage-through chamber 2 has on both sides of the form box 4 a burner chamber each. There are chamber sections of the passage-through chamber 2, in which chamber sections terminate feeding conduits 7, which are connected with a feeding device 8, by means of which a gaseous, combustible mixture can be controllably and regulatably supplied into the burner chambers 6. The combustible mixture is fed not only controlled and proportioned alternately or fed also simultaneously into both burner chambers 6, rather a temperature control takes place by means of a control device 9, and in addition a mixture control is performed by means of a control device 10, which varies the ratio of the quantities, in which gaseous fuel and air are divided, depending upon predetermined presumptions.

On both sides of the form box 4 are provided heat storages 11 outside of the burner chambers 6. These heat storages 11 are formed permeable. A gas cooler 12 follows the heat storage in the direction of the passage-through. chamber 2 in accordance with the embodiment disclosed in FIG. 1. The exit sides of the gas cooler are connected together by means of a conduit 13.

A gas feeding device 14 is connected with the conduit 13, which device 14 is equipped for reversing the direction of feeding, by providing, as shown in FIG. 1, a blower 15 with a stream reversal device 16. In view of the reversal device 16, the blower 15 can be operated in the same rotary direction, while the flow direction of the gas in the conduit 13 can be varied dependent upon the position of the reversal device 16. A flue gas branch 17 can be connected with the suction branch of the blower 15.

The apparatus shown in FIG. 1 and described above has a substantially constant gas volume. When the state indicated in FIG. 1 prevails, the gas flows in the direction of the arrows 18 (FIG. 1). The gas has within the range of the conduit 13 a comparatively low temperature, which can be below 400 C. In the direction of flow shown in FIG. 1 the gas enters from the conduit 13 into the passage-through chamber 2 through the gas cooler 12 shown in FIG. 1 at the upper end. The gas cooler 12 can be taken out of operation at the moment of the entrance of the gas. The gas passes after its entrance in the passage-through chamber 2 the upper heat storage 11 and enters the upper burner chamber 6. In case there are not certain conditions, as, by example, an oxidizing or reducing gas character or other measures make it necessary, no additional heating of the gas is provided in the upper burner chamber 6. Rather the gas in the upper heat storage 11 is heated by its previous heating to the required working temperature and, depending upon the working conditions to temperatures of a range between 1100 C. and 1200 C. The highly heated gas flows now through the heap of debris of the granulate 3 in the form box 4 and up in the lower burner chamber 6 by feeding in a gas eous combustible mixture through the entrance opening of the feeding conduit 7. Then the gas flows through the lower heat storage 11 and heats the latter, after passage of the lower heat storage 11, the gas has a comparatively low temperature and can be cooled once more in the lower gas cooler 12, so that it can enter with a low temperature the conduit 13 and can be fed to the gas feeding device 14. For this purpose a cooling medium is fed to this gas cooler 12 in the direction of the arrows 19 (FIG. 1). For a reversal of the direction of the flow, it is merely necessary to reverse the reversaldevice 16. The described process runs then in corresponding manner with a reversed direction of flow of the gas.

The described apparatus is characterized such, that high gas temperatures rule only in the range of the burner chamber 6, which are disposed adjacent both heat storages. The ratio of the temperatures of the gas, within this range to the temperatures, which rule, by example, in the conduit 13, can be of the order of about 3:1. Correspondingly a similarly large volume ratio results. This means, that the conduit 13 as well as the gas feeding device 14 are not subjected to high temperatures and can be made accordingly of conventional working material. The gas feeding device 14 has to move also only comparatively low gas quantities, in order to assure a predetermined gas passage in the form box 4. The flue gas branch 17 provided on the gas feeding device 14 serves the purpose, 'to maintain constant the gas volume in the apparatus 1, by feeding off the gas quantities produced additionally by the operation of the burner chambers 6. This feeding off takes place, however, in a place, at which the gas has a very low temperature, so that heat losses are excessively avoided.

The described apparatus shown in FIG. 1 operates also with a high efficiency, since the high gas temperature required for the swellingand ceramic bindingprocess prevails only within the chamber range between the heat storages 11, whereby the heat quantity and heat content of the gas volume, respectively, be tween the two heat storages moves steadily back and forth like a pendulum movement and is completed if necessary corresponding with the operation of the burner chambers and the burner-chamber-feeding device 8, respectively.

For the production of ceramically bound bodies of bulking clay it is advantageous, if the change of direction of the gas takes place as much as possible free of retardations. In the apparatus disclosed in FIG. 1 this change of direction can be performed relatively fast, because no moving parts, as by example ventilator wheels or the like must be stopped and driven again.

Referring now again to the drawings, and in particular to FIG. .2, a further embodiment of the apparatus disclosed in connection with FIG. 1, is shown. The passage-through chamber 2 is shown here in full view with the body 1, because the range between the heat stor ages 11 is identical with the embodiment of FIG. 1. In the embodiment of FIG. 2, the gas coolers 12 are omitted and also the conduit 13 is not provided. A chamber section 19 follows in the passage-through chamber 2 directly to the heat storage 11, in which chamber section 19 a piston 20 is guided slidingly as a gas feeding device 20. The pistons 20 are connected together for driving such, that they are moved in opposite directions by means of coupled driving devices 21. It is to be recognized, that in case of a downwardly directed movement of the upper piston of FIG. 2 and a corresponding upward movement of the lower piston of FIG. 2 the same gas flow conditions are produced in the passagethrough chamber 2, as explained in connection with FIG. 1. Due to the fact that the upper piston produces over pressure and the lower piston a depression, a strong pressure drop results, which is a presumption for the desired gas speed during passage of the form box. In order to drive with each working play also the desired gas quantity through the form box 4, care must be taken for a corresponding stroke of the pistons 20 or for a corresponding cross-section of the chamber sections.

Since in the embodiment of the apparatus according to FIG. 2 a conduit 13 as shown in FIG. 1, connecting the exit sides and the chamber sections 19, respectively, is missing, it is required to provide two flue gas branches 17', which terminate in the chamber sections 19. Suitably these flue gas branches 17' are equipped with corresponding locking members, so that a controlled opening and closing is possible.

Referring now to the embodiment of FIG. 3, the design of the passage through chamber 2, is again identical with that of FIG. 1. Deviating from the embodiment of FIG. 1, the design of the gas feeding device 14 which is built in the conduit 13, is changed. In the embodiment of FIG. 3 the gas feeding device 14 has a double piston 22, which is guided tightly sliding in a middle section of the conduit 13". The section 24 of the conduit 13 disposed between the pistons 22 connected mechanically by means of a piston rod 23 is divided by a separation wall 25 into two pressure chambers 26 and 27, which can be controlled by a pressure medium by means of a valve control device 28 from a source (not shown). If the pressure chamber 26 is subjected to pressure, then the double piston 22 is driven in the direction of the arrow 29 in upward connection (FIG. 3) and the same gas flowing conditions prevail, corresponding to the arrows 18 in FIG. 1. For a reversal of the flow direction, it is merely necessary to subject the chamber 27 to pressure.

The advantage of the use of the pistons 20 and of the double pistons 22 compared with a blower l5, resides in the fact, that relatively such gas volumes suffice, which can be moved within a short time period in opposite directions, while a blower requires a comparatively larger volume, in order to be operative.

The burner feeding device 8, can have, in accordance with FIGS. 2 and 3 in addition to the conduits 7 leading to the burner chambers 6 for the mixture or combustion gas additional feeding conduits 8a and 8b, which terminate either in the chamber sections 19 (FIG. 2) or in the pressure chambers 26 and 27 (FIG. 3) and feed thereto combustion air. By'means of these conduits 8a and 8b the combustion air required for the mixture formation can be fed selectively totally or proportionally to the chamber sections 19 or the pressure chambers 26 and 27, respectively. The feeding takes place into that chamber section or pressure chamber, in which the over pressure prevails. This proceeding leads to the fact, that the oxygen is fed to the combustion air of the burning chamber in strong dilution. This leads to a retardation of the combustion process in the burner chambers. If the mixture disposed in the burning chambers passes however, the heap of debris in the form box, then the granulate operates as a catalyst, which causes an immediate combustion of the mixture, so that the heat is produced directly at the place of the requirement.

The arrangement of the conduits 8a and 8b for the combustion air can of course, be provided also in the embodiment of FIG. 1, in which this conduit is not shown for the sake of clarity.

Referring now again to the drawing and in particular to FIG. 4. This embodiment is a particularly interesting further development of the apparatus of FIG. 1 with a special arrangement of the conduits for the combustion air. In this development the conduit 13 leads directly into the passage through chamber 2. Instead of two gas coolers only one gas cooler 12 is provided, which is disposed between the diversing device 16 and the suction branch of the blower 15". The flue gas branch 17 is connected between the gas cooler 12 and the blower 15'. The burner feeding device 8 has in addition to the feeding conduit 7 to the burner chambers a feeding conduit for the combustion air, which terminates between the connection place of the flue gas branch 17 and the blower 15 into the suction tube. In addition to the saving of a second cooler in this embodiment the advantages of the mixture feed set forth above in connection with the embodiments of FIGS. 2 and 3 are achieved.

While I have disclosed several embodiments of the present invention, it is to be understood that these embodiments are given by example only and not in a limiting sense.

I claim:

1. An apparatus for the production of ceramically bound bodies of bulking clay comprising a housing defining a passage-through chamber,

adapted to blow alternately highly heated gas in opposite directions through a heap of debris of a granulate capable of swelling in a form box received in said chamber up to swelling and ceramic binding of the surfaces of said granulate,

a gas feeding device,

a heat storage,

said passage-through chamber including said heat storage in the direction of the flow of said gas driven alternately back and forth on both sides of said form box,

a burner feeding device for a gaseous mixture and operating controlled and regulated,

chamber sections disposed between said heating storage and said form box, said chamber sections constituting burner chambers, and a flue gas branch disposed within the range of said gas feeding device.

2. The apparatus, as set forth in claim 1, wherein said gas feeding device has a controlingly driven double piston in the gas flow path, which moves back and forth the substantially closed gas volume between said pistons through said form box, said burner chamber and said heat storage.

3. The apparatus, as set forth in claim 2, wherein said double piston is disposed in a conduit, and

said conduit follows on the down stream side of said heat storage.

4. The apparatus, as set forth in claim 1, wherein said gas feeding device comprises two mechanically separated yet drivingly connected individual pistons,

9 10, one of said pistons being disposed on the downstream said gas feeding device includes: at least one pressure flow path behind each of said heat storages in said producing piston, and passage-through chamber. said conduits feeding combustion air selectively at 5. The apparatus, as set forth in claim 1, wherein least partially into the flowing path in front of said said gas feeding device comprises a reversing controlpressure producing piston.

lable blower and disposed in a conduit, and 8. The apparatus, as set forth in claim 5, wherein said conduit connects the downstream side of said said burner feeding device includes a conduit for heat storages. combustion air terminating at the suction side of 6. The apparatus, as set forth in claim 5, which insaid blower between said flue branch and said cludes 10 blower, and adapted to feed said combustion air at least one gas cooler disposed between said gas required for the mixture formation selectively confeeding device and said heat storage. trolled at least partly into said gas outside of said 7. The apparatus, as set forth in claim 1, wherein burner chambers. said burner feeding device includes conduits, "f 

1. An apparatus for the production of ceramically bound bodies of bulking clay comprising a housing defining a passage-through chamber, adapted to blow alternately highly heated gas in opposite directions through a heap of debris of a granulate capable of swelling in a form box received in said chamber up to swelling and ceramic binding of the surfaces of said granulate, a gas feeding device, a heat storage, said passage-through chamber including said heat storage in the direction of the flow of said gas driven alternately back and forth on both sides of said form box, a burner feeding device for a gaseous mixture and opErating controlled and regulated, chamber sections disposed between said heating storage and said form box, said chamber sections constituting burner chambers, and a flue gas branch disposed within the range of said gas feeding device.
 2. The apparatus, as set forth in claim 1, wherein said gas feeding device has a controlingly driven double piston in the gas flow path, which moves back and forth the substantially closed gas volume between said pistons through said form box, said burner chamber and said heat storage.
 3. The apparatus, as set forth in claim 2, wherein said double piston is disposed in a conduit, and said conduit follows on the down stream side of said heat storage.
 4. The apparatus, as set forth in claim 1, wherein said gas feeding device comprises two mechanically separated yet drivingly connected individual pistons, one of said pistons being disposed on the downstream flow path behind each of said heat storages in said passage-through chamber.
 5. The apparatus, as set forth in claim 1, wherein said gas feeding device comprises a reversing controllable blower and disposed in a conduit, and said conduit connects the downstream side of said heat storages.
 6. The apparatus, as set forth in claim 5, which includes at least one gas cooler disposed between said gas feeding device and said heat storage.
 7. The apparatus, as set forth in claim 1, wherein said burner feeding device includes conduits, said gas feeding device includes at least one pressure producing piston, and said conduits feeding combustion air selectively at least partially into the flowing path in front of said pressure producing piston.
 8. The apparatus, as set forth in claim 5, wherein said burner feeding device includes a conduit for combustion air terminating at the suction side of said blower between said flue branch and said blower, and adapted to feed said combustion air required for the mixture formation selectively controlled at least partly into said gas outside of said burner chambers. 